similar to the act of a jack-in-the-box, but rather when one flips up the toilet seat and finds a disgusting piece of old, yellow-brown, shit sitting at the bottom of the comode; this is usually done as a joke to show off your big load to a friend or relative, and is very rude because they didnt flush it down

i saw the worst poop-in-the-john this morning, my brother said he dropped it the night before, which explained the absurd shape and color of it